Here is a quick list of the Playboy Centerfold locations in Mafia II. For pictures and in-depth descriptions for each Centerfold, be sure to check out IGN's Mafia II Guide.
http://guides.ign.com/guides/957837/page_4.html

* Playmate 1 - Chapter 2 "Follow Joe to his Garage" // On Joe's coffee table
* Playmate 3 - Chapter 2 "Car Crusher" // On shelf in three-car garage
* Playmate 18 - Chapter 3 "The Southport Docks" // On floor outside Derek's office
* Playmate 4 - Chapter 3 "Drive to Maria Angello's" // On the floor of Maria's apartment behind the door
* Playmate 5 - Chapter 3 "Get Inside the Office" // In the Industrial Specialists Office on the windowsill
* Playmate 40 - Chapter 3 "Get Inside the Office" // On the first floor security guard desk
* Playmate 6 - Chapter 3 "Get Inside the Office" // On the floor of the basement stoarage room
* Playmate 9 - Chapter 4 "Get Out of the Mall" // In a box on the first stairwell landing
* Playmate 2 - Chapter 4 "Get Out of the Mall" // By locked doors in the second stairwell after the bookstore
* Playmate 8 - Chapter 4 "Fend off the Cops" // On floor of the rooftop structure
* Playmate 7 - Chapter 4 "Go to Sleep" // At the bottom of the stairs (don't go into the apartment)
* Playmate 11 - Chapter 5 "Kill the Fat Man" // Exit the apartment with Henry and Joe and take the stairs up
* Playmate 10 - Chapter 5 "Kill the Fat Man" // Quickly get to the first floor distillery office, it's on a shelf
* Playmate 12 - Chapter 5 "Kill the Fat Man" // On the 5th floor, look to the right as you escort Henry
* Playmate 13 - Chapter 6 "Contact Leo Galante" // Under the sleeping prisoner
* Playmate 14 - Chapter 6 "Contact Leo Galante" // Search behind the grey shack by the basketball court
* Playmate 15 - Chapter 6 "Go to the Guard" // On top of the large drying machine
* Playmate 16 - Chapter 7 "Playmate 16" // Catch Up with Joe - On the floor of the gun store near the stairs
* Playmate 50 - Chapter 7 "Drive with Joe to Apartment" // At the end of the hall on the top floor
* Playmate 17 - Chapter 7 "Drive with Joe to Apartment" // On the hallway table on the second floor
* Playmate 46 - Chapter 7 "Drive with Joe to Apartment" // On the kitchen table in the apartment
* Playmate 19 - Chapter 8 "Take Out the Greasers" // In a shack around the corner in the foundry
* Playmate 21 - Chapter 8 "Take Out the Greasers" // On the ground near some oil drums
* Playmate 20 - Chapter 8 "Take Out the Greasers" // Search the narrow alley to the left of the mob, it's in a shack
* Playmate 41 - Chapter 9 "Head to Maltese Falcon" // Lying on the bar
* Playmate 23 - Chapter 9 "Find Way into Slaughterhouse" // Search the tunnel to the left of the sewage dump
* Playmate 22 - Chapter 9 "Slaughterhouse Interior" // On the floor in the first slaughterhouse area
* Playmate 24 - Chapter 9 "Save Your Guys" // On a shelf in the back corner near the entrance
* Playmate 25 - Chapter 10 "Find Cleaners Uniform" // On a desk in an office in the rear of a laundry area
* Playmate 27 - Chapter 10 "Follow Joe to Roof" // On the floor downstairs -- don't follow Joe upstairs
* Playmate 26 - Chapter 10 "Find Window Washing Platform" // On the floor by the elevator power source
* Playmate 48 - Chapter 11 "Get the Door" // On the bathroom floor
* Playmate 47 - Chapter 11 "Drive Leo to Train Station" // Search the second floor of the house, it's on a window sill in the hallway
* Playmate 29 - Chapter 11 "Drive Leo to Train Station" // Search the second floor of the house, it's in the bathroom
* Playmate 28 - Chapter 11 "Go Home" // On the bedroom floor
* Playmate 49 - Chapter 11 "You Must Get Dressed" // On the floor by Joe's bed
* Playmate 30 - Chapter 11 "Catch Irish Leader" // Under a box in the end of the hallway
* Playmate 32 - Chapter 12 "Drive to Seagift Warehouse" // Between the delivery truck and the crates
* Playmate 31 - Chapter 12 "Drive to Seagift Warehouse" // In an alley behind some dumpsters
* Playmate 33 - Chapter 12 "Get Out of Here!" // Under the green power panel on the wall
* Playmate 34 - Chapter 13 "Find Wong" // In the rear corner of the main dining area
* Playmate 36 - Chapter 13 "Find Wong" // In the opium den, on a wooden crate
* Playmate 35 - Chapter 13 "Find Wong, Basement" // In the basement of the armory on a box
* Playmate 44 - Chapter 14 "Get Out of the Building with Joe" // Search the narrow area on the eastern edge of the building
* Playmate 37 - Chapter 14 "Floor 3" // On a stack of burning pallets
* Playmate 38 - Chapter 14 "Floor 3" // In the rear corner of the room with a single shooter
* Playmate 45 - Chapter 15 "Observatory" // In the first floor stairwell
* Playmate 39 - Chapter 15 "Observatory Roof" // Search the western edge of the roof
* Playmate 43 - Chapter 15 "Observatory Interior" // Behind the telescope, staircase
* Playmate 42 - Chapter 15 "Leave the Observatory" // At the base of the observatory projector

Trophies
Complete the following tasks to unlock PlayStation3 trophy rewards.
Viva la Resistenza! (Bronze): Complete Chapter 1.
Home Sweet Home (Bronze): Complete Chapter 2.
Back in Business (Bronze): Do your first job for Mike Bruski.
Big Brother (Bronze): Protect Francesca.
A Real Gentleman (Bronze): Help the woman fix her car in Home Sweet Home.
The Price of Oil (Bronze): Complete Chapter 3.
The Professional (Bronze): Obtain the ration stamps without raising the alarm.
Mail Man (Bronze): Sell all the gas stamps before the time runs out.
Night Shift (Bronze): Complete Chapter 4.
Good Spirits (Bronze): Complete Chapter 5.
Time Well Spent (Bronze): Complete Chapter 6.
Last Respects (Bronze): Complete Chapter 7.
The Wild Ones (Bronze): Complete Chapter 8.
Man of Honor (Bronze): Complete Chapter 9.
Checking Out (Bronze): Complete Chapter 10.
Our Good Friend (Bronze): Complete Chapter 11.
Wake Up Call (Bronze): Help Leo out of a tricky situation without getting caught.
Chasing the Dragon (Bronze): Complete Chapter 12.
Chop Chop! (Bronze): Complete Chapter 13.
Get Rich or Die Flyin' (Bronze): Get all wheels of your car into the air for at least 20 meters and then touch the ground again.
Pedal to the Metal (Bronze): Travel at 125 mph.
One Careful Owner (Bronze): Travel a total of 50 miles in one vehicle.
Proper Scapper (Bronze): Sell 5 vehicles to Mike Bruski at the scrapyard.
Exporter (Bronze): Sell 5 vehicles to Derek at the dock.
Cruise Control (Bronze): Keep any vehicle at 30 mph or over for 5 or more minutes.
Hairdresser (Bronze): Kill 5 enemies in rapid succession with a headshot.
Knucklehead (Bronze): Kill a total of 30 enemies using melee attacks.
Stuck Up (Bronze): Rob 5 stores in under 5 minutes.
The Enforcer (Bronze): Kill 50 enemies.
Sharp Suiter (Bronze): Buy your first luxury suit.
Tuned Ride (Bronze): Upgrade one of your cars one level.
Dream Handling (Bronze): Upgrade one of your cars to the maximum level.
Hard to Kill (Bronze): The police want you dead. Survive for 10 minutes!
Collector's Item (Bronze): Find at least one collectible in the game.
Petrol Head (Bronze): Drive at least 30 different vehicles.
Met at Work (Silver): Complete Chapter 14.
Finish Him (Silver): Finish what you started.
Ladies' Man (Silver): Find all of the Playboy magazines.
Card Sharp (Silver): Find all of the Wanted posters.
He Who Pays the Barber (Silver): Improve the dockworker's haircuts.
A Lesson in Manners (Silver): Show that you know how to treat a lady.
Hey Joe (Silver): Clean up after Joe.
End of the Rainbow (Silver): Settle the score with the Irish once and for all.
The Mafia Never Forgets (Silver): Pay a visit to an old friend.
Out for Justice (Silver): Learn what it means to be a Scaletta.
Made Man (Gold): Finish the story on Medium difficulty or higher.
Tough Nut (Gold): Finish the story on Hard difficulty level.
Platinum Trophy (Platinum): Unlocked when all trophies collected.